1. Field of the Invention
The present invention relates to a storage device and a performance measurement method for the device, and especially, is suitable when applied to a storage device written with data by a plurality of host devices, and a performance measurement method for the device.
2. Description of the Related Art
For measuring the performance of a storage device, basically needed is the function of I/O (Input/Output) issuing and measurement. For I/O issuing, there needs to designate a target device, and designate and control a load. Such designation and control are made normally on a host device. Note that a read/write command coming from the host device is executed generally on the basis of a logical volume of a storage device called LU (Logical Unit).
The storage device of a large size is designed to be connected with a plurality of host devices, and with the recent advance of technology, the LUs definable in the storage device are now larger in number than the number recognizable by a piece of host device. This thus causes a need for a plurality of host devices for measuring the performance of the storage device.
For measuring the performance in terms of specific factors, by utilizing the functions on the storage device side, i.e., monitoring and load managing, the logical volumes can be measured in its entirety all at once. The specific factors include an I/O response time, the number of I/Os, a disk occupancy rate, the number of CRC (Cyclic Redundancy Check) errors, which can be measured at fixed time intervals for each of the logical volumes. An example includes Patent Document 1 (JP-A-2007-323560). Moreover, for each of the LUs, the transfer performance and the load status can be measured in each internal bus, and a notification can be made to other components. An example includes Patent Document 2 (JP-A-2002-215335). Measuring an average I/O response time is also possible for load control in accordance with the host device I/O. An example includes Patent Document 3 (JP-A-2004-206623).
The issue here is that a software package operating on the host devices has a recognition limit for the number of LUs, and thus a large number of LUs cannot be measured all at once. Another issue is that, even if a plurality of host devices individually perform the load measurement with respect to the LUs, the measurement environment will not be the same because the host devices each have their own hardware and software environment. As such, collectively measuring a large number of LUs in the storage device is considered significant. Moreover, due to the varying path lengths from each of the host devices to the storage device, the measurement performed on the side of the host devices resultantly includes not only the operating load of the host devices but also the communications load, thereby failing to be accurate.